1. Field of the Invention
The invention relates to flow control devices and, in particular, to a flow control having a flow control washer that maintains a generally constant volumetric flow rate through a liquid stream despite fluctuations in supply pressure.
2. Description of the Related Art
Flow controls are commonly used in appliances such as dishwashers, drinking fountains, and water softeners to compensate for variations in water supply pressure. The typical flow control comprises an annular flexible flow control washer mounted in a conduit such that water flowing through the conduit must flow through a central orifice in the flow control washer. The flow control washer and its support in the conduit are configured so that the orifice constricts as the water pressure increases, thereby maintaining a generally constant volumetric liquid flow rate through the conduit despite variations in supply pressure. A flow control of this general type has been used in water softeners as is detailed in U.S. Pat. No. 4,210,532 to Loke and in U.S. Pat. No. 5,162,080 to Dragger.
Flow controls of the above-mentioned type tend to be very noisy in operation, possibly due to cavitation caused by the pressure drop across the washer and/or to vibrations of the washer itself. In fact, in the case of a water softener, the whistling noise generated by the flow of water through the flow control can often proprogate through the pipes and be heard throughout much of the building.
This noise problem has been recognized and addressed, but never satisfactorily. For instance, U.S. Pat. No. 5,226,446 to Cooper proposes a rather complex anticavitation arrangement disposed downstream of the flow control washer. U.S. Pat. No. 3,250,342 to Petry proposes an expansion duct having apertures to recycle a portion of the fluid flow. U.S. Pat. No. 3,712,341 to Constantin proposes a flow separator for separating a downstream fluid influx from an upstream fluid flow. All of these arrangements are relative complex, are relatively expensive to manufacture and install, and are of questionable effectiveness.
In view of the foregoing, it would be desirable to provide a flow control that solves the noise problems associated with prior flow controls in a simple and effective manner.
The invention, which is defined by the claims set out at the end of this disclosure, is intended to solve at least some of the problems noted above. In accordance with a first aspect of the invention, the above-identified need is satisfied by providing a flow control comprising a conduit and flow control washer disposed in the conduit between its inlet and its outlet. xe2x80x9cConduit,xe2x80x9d as used herein, means an enclosed passageway capable of receiving a flow control washer. An ambient fluid passageway opens into the conduit, preferably at a location just downstream of the flow control washer, to permit a gas (typically ambient air) to enter a liquid stream flowing from the flow control washer. The admission of the gas into this liquid stream reduces noise generated by liquid flow through the flow control washer. Gas induction and noise reduction capabilities may be enhanced by admitting the gas into a low pressure region of a venturi located in the conduit adjacent the flow control washer. The venturi may be formed integrally with the conduit or provided as a separate insert fitted in the conduit.
A method of reducing noise in a flow control is also provided. In the method, liquid flows through a flow control washer of a flow control conduit at a volumetric flow rate that remains generally constant, despite pressure fluctuations in the flowing liquid, due to operation of the flow control washer. A gas (typically ambient air) is drawn into the liquid flow to reduce the noise that would otherwise be generated by operation of the flow control.
The flow control can be used in any application where the flow rate is controlled within a particular pressure range. Examples of uses for the flow control include, but are not limited to, water softeners, water fountains, eye washes, dishwashers, and safety showers. If used on conjunction with a simple on/off valve, it can also be used do measure or dispense a given volume of fluid, without having to make volumetric measurements, simply by relying the flow control to maintain a desired fluid flow rate therethrough and automatically or manually closing the valve at the appropriate time. Hence, if a flow control maintains a flow rate therethrough at 2 gpm, 20 gallons can be reliably measured or dispensed simply by closing an associated valve after 10 minutes of flow through the flow control.
These and other objects, advantages, and features of the invention will become apparent to those skilled in the art from the detailed description and the accompanying drawings. It should be understood, however, that the detailed description and accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation.